Machine gun feed mechanism



Dec. 4, 1945. J. c. TROTTER 2,390,477

MACHINE GUN FEED MECHANISM Filed Feb. 7, 1941 6 Sheets-Sheet l INVENTOR JOHN C. 7'R07'7'ER Dec. 4, 1945. Y J, c TROTTER 2,39%,4?!

MACHINE GUN FEED MECHANISM Filed Feb. 7, 1941 6 Sheets-Sheet 2 INVENTOR JOHN e. 772077572 1945- J. c. TROTTER MACHINE GUN FEED MECHANISM Filed Feb. "7, 1941 6 Sheets-Sheet 3 INVENTOR Jw-w 0. 72077-5? Dec. 4,

J. c. TROTTER 2,390,477

MACHINE GUN FEED MECHANISM Filed Feb. 7, 1941 6 Sheets-Sheet 5 l N V E NTO R ./a///v 6. 7207/5? N EYS Dec. 4, 1945. J. c. 'I'RQJ TER 2,390,477

- MACHINE GUN FEED MECHANISM Filed Feb. 7, 1941 6 Sheets-Sheet 6 'l l l l INVENTOR r ATT N EYS Patented Dec. 4, 1945 MACHINE GUN FEED MECHANISM John C. Trotter, Williamsville, N. Y., assignor to Bell Aircraft Corporation, Bufialo, N. Y.

Application February 7, 1941, Serial No. 377,819

4 Claims.

This invention relates to machine guns, and more particularl to improved means for feeding of ammunition thereto.

Modern machine gun installation designs tend to involve provision for continuously increasing ammunition magazine capacities, whereby the cartridge belts are required to be pulled over increased distances and the loads upon the gun feed mechanisms are consequentl increased. Also, because of the modern tendency to increase the caliber of the cartridges used, the weights of the cartridge belts are also thereby increased, and the gun feeding mechanisms are required to supply substantial amounts of power to the moving of the cartridge belts. Because of definite limitations with respect to strength and power supplying abilities of the usual gun feed mechanism per se, I have found that it is of utmost importance and desirabilit to supplement the action of the usual gun feed mechanism by means of an accessory feed assist mechanism so that previous limitations as to location of the magazine relative to the gun are no longer deciding factors with respect to the design of the gun and gun feed installation. This is of particular importance, for example, in connection with modern combat airplane construction because of certain space limitations which are inherentl present in connection with airplane design.

The present invention contemplates the disposition of the cartridge belt magazine at any desired location relative to the gun, as for example at a relatively remote location within an enclosing airplane wing structure or the like; and the magazine will be of any suitable configuration so as to be effectively nested within the compass of the supporting structure without regard to the length and weight of the unsupported belt portion to be motivated in connection with its feeding into the gun. A feed assist mechanism of novel character is arranged between the magazine and the gun and is operatively coupled with the cartridge belt in such manner as to be adapted to take substantially all of the loads in connection with feeding the belt to the gun. The assist magazine is arranged to be of such character as to avoid overrunning the feed requirements of the gun feed mechanism per se; and thus uniform feeding of the gun is provided in an improved manner and jamming of the gun feed operation is avoided. Other objects and advantages of the invention will appear from the specification herein.

In the drawings:

Fig. 1 is a fragmentary side elevation of a machine gun and assist mechanism of the invention,

with portions broken away to reveal the interior thereof;

Fig. 2 is a view taken substantially along the line IIII of Fig. 1;

Fig. 3 is a View corresponding to Fig. 2 showing another form of assist mechanism;

Fig. 4 is a section, taken substantially along line IV-IV of Fig. 3;

Fig. 5 is a top plan of a machine gun and an assist mechanism control device of another form thereof; and

Fig. 6 is an enlarged view of the control device portion of Fig. 5, with portions broken away to reveal the interior thereof.

Fig. 7 is a diagrammatic view of the control switch and power circuit of the mechanism of Figs. 3 and 4; and

Fig. 8 is a diagrammatic view of the control switch and power circuit of the form of the invention illustrated by Figs. 5 and. 6.

The invention is illustrated in Figs. 1 and 2 in conjunction with a machine gun 10 having a cartridge pawl l2 (Fig. 2) in association with the cartridge inlet port thereof, in accord with usual machine gun practice. The cartridge belt magazine I4 is shown at; a location spaced from the gun I0, and a belt feed assist mechanism of the invention is shown disposed between the gun I0 and magazine It. The feed assist mechanism includes a tubular throat piece I6 which is flared at its outer end ll to provide smooth flow of the cartridge belt thereinto from the magazine I4. The magazine is also shown as being provided with rollers l8 for guiding the cartridge belt as it emerges from the magazine in smoothl moving manner. The throat I6 is supported upon a bracket l9 so as to extend at its inner end portion 20 into registry with the cartridge inlet port of the gun It, and it will be understood that the throat i6 is of suitable rectangular sectional form and dimensions so as to freely accommodate the cartridge belt in smooth sliding relation therein. A pair Of driving rolls 22-44 are rotatably mounted upon parallel shafts 26 and 27, respectively, so as to be disposed in spaced relation and at opposite sides of the cartridge belt as it passes through the throat IS. The rolls 22 and 24 are provided with enlarged heads 28 at opposite ends thereof, and the heads 28 are peripherally escalloped as illustrated in Fig. 2 so that the rolls 22 and 24 are adapted to engage the individual cartridges 30 of the cartridge belt as they pass therebetween in geared relation. The driving roll 24 is keyed to the shaft 26 which extends into connection with the inner end of a coil spring 34. The outer end of the coil spring 34 is connected as at 35 to a cylindrical housing 3! which is in turn keyed at 38 to the driven shaft it of a reduction gear unit i2. atively coupled with the armature of an electric motor 45 which is also mounted upon the bracket is. The motor 55 is arranged to be energized from any suitable power source operating through operation will be automaticallyaccompanied.by"

stopping of the motor driving action. Thus, the

driving rolls 22-24 are adapted to feed the belt ofcartridges 39 into the gun it generally in accord with its requirements, and to thus relieve the gun feed .inechanism ofthe gun of the loads involved in pulling the belt out of the magazine l4 andinto the feed throat/l5. ,7

Preferably, the motor flfi will be of. the socalled hightorque .typeandadapted to run at various speeds without damage to its windings, so that under relativelyv slow firing conditions the back pressureo'f the cartridge belt into the throat It will simply retard the speed of the driving m otor. Preferably, the gear reduction device lZwillbe of irreversible character. so that reverse movement of the driving mechanism will not be possible when the .motor. dais ie-energized. Thus the deviceof the invention is adapted to provide a cartridge belt feeding operation which involves driving .:.of thecartridge belt through the feed throat it. upon operation of the driving motor 45, and simultaneous storing of energy within the coil springgs, ,dueto the attempt of the driving --motor to.overrun the speed of cartridge reception.

The driving shaft 34 of the gear unit is oper- I by the feed mechanism of the gun. Upon interruption. of the. gun firinghoperation the stoppage of the gun feed mechanism will immediately halt movement of the. cartridge belt-through the feed throat. I6; and thus th driving rolls Z 2 24;Wi 1l be. halted while the ,momentumof the mgving partsofthe motorand associated driving mechanism willbe dissipated in, further tensioningof the couplingspring 34. Due to the irreversible character of the gear mechanism 452 the energy thusstoredin thecoupling springs}! will be retainedthereinppending further operation of the gun. Upon subsequent reclosingof the gun flrng switch and recommencement .of the firing operation.,the motor 55 will be re-energized, and while the motor is picking up its fulloperating speed .it. will initially lag behind the, required corresponding speed forfeeding the cartridge belt in accord with .the usual requirements of. the gun.

. However, during this period of initial motor speed 'lag the coupling spring 34 will extend tomake up .for the. deficiency in thedriving motor speed, and

thus there is provided an automaticallyuniform belt feeding pressure at all stages of the gun firing operation.

v ,,.r. i s. 3 and 4 illustrate ana ram a the in- .vention wherein the feed assist mechanism is 10- catedbetween the magazine it and the gun I0 and. includes a cartridge feed throatBi] which i'sgenerally similar, to the feed throat I6 of Figs.

.1 and .2. .The throatjtil .is rigidly. mounted upon a fixed bracketfil. A pairofdopp'osed driving rolls .52. and. 5 lwhich'aregenerally similar to the'driving rolls 22-16 hereinabove described are mounting r011 52.

ed in similar relation except that the upper roll 54 is rotatably mounted upon the feed throat 50 and the lower r011 52 is rotatably mounted upon a yoke 56 which is in turn pivotally mounted by means of a pint? upon the bracket at. A crank arm 58 extends below from the yoke 55 into pivotal connection at 59 with one end of a compression strut 6G. The compression strut Bil is normally maintained in the condition illustrated in Fig. 3 by means of a compression spring Sl thereof; the strut 68 being pivotall mounted at its opposite end by means of a pin E2 to a portion of thefixed bracket 5!. diametrical opposed location with respect to its connection atIESQ; the yoke 58 is arranged to bear against theexteiiding finger portion 65 of a spring finger electric. switch 65 which is mounted upon the bracket 5!. Thus, the force of the compression spring (it normally maintains the yoke .58 in the position of Fig. 3 whereby the lower roll 52 is in vertical alignment with'the upper roll 54 and the finger 65 of the switches is depressed in .suchma'nner as, toclose the electric circuit with which the switch 66 is associated. In Fig. 7 the switch 66 is illustrated as comprising a leaf spring contact member 61 adapted to be pressed by the finger 65 into contact with a fixed contact point 58 for closing the electric circuit controlling the driving motor which is illustrated inFig. 4 at 73. A spring 69 is arranged to repel the finger 65 whenever the roll 521s backed away from the switch as. will be explained hereinafter. As in the case ofthe motor 45 of Figs. 1 and 2, the motor, 7B is operatively coupled to an irreversible gear reduction. device .72 by a drive shaft 13. The driven shaft Id of the reduction gear device is operatively coupled through means of a-pair of universal joints l5 and an intermediate drive shaft 15 with a torque tube T! which is operatively connected to the inner end portion of a coil spring was in the manner of the connection between the. shaft 32 and thespring 340i Fig. 1. The

outer end portion of the spring 78 is fixed to a housing member B ll which is rotatably carried by means of a central. bore upon a drive shaft 82 which extends, into keyed relation with the driv- The drive shaft 32 is rotatabl carried on opposed wall portions of the yoke 58, and thus the, roll 52 is rotatably mounted upon the yoke. The'housing .38 is connected at an extended centralportion 84 to the inner end portion of asecond coil spring 86 which is similar to the spring 18 and connectslat its outer end to a second housing member 83. The second housing member88 is keyedto the drive shaft 82 at 89.

Thus, beginning. from acondition ofnon-operation, upon closing .of. the gun firing switch the machine'gun It) will commence firing and the recoil actuated cartridge ifeedmechanism thereof will operate to draw the belt of cartridges through the feed throat 5t. Simultaneously with commencing. of the firing operation of the gun,

the .motor .10 will be energizedbecause of. the closed circuit position of the switch 68. Thus, the motor 10 will'operate through'the gear and universal jointand spring coupling mechanism to rotate. the drive shaft 82, whereupon the driving rolls 52 and '54 will operate toidrive the cartridge .belt through the feed throat 53 and to thus relieve the gun feed mechanism of the loads of drawing the cartridge belt outfif the magazine l4. Subsequent to attainment of full driving speed on. the part'of the motor-.76, the. coupling sprin devices wand 88 wi1l;.0perate toabsorb overrunning movements of the motor it relative to At its upper end and at a r the cartridge belt feeding operation; and thus the coupling springs will be tensioned with roll driving energy. Upon interruption of the gun firing operation the movement of the cartridge belt to the feed throat 50 will be halted, but the motor 70 will continue momentarily to cause the driving roll 52 to be rotated. Since the belt of cartridges in the feed throat 50 is now positively halted because of stoppage of the gun feed mechanism, and because the drive shaft 82 of the roll 52 is mounted upon the pivotal yoke 50, the yoke 56 will then be caused to pivot upon the pin I.against the action of the strut spring GI to permit the upper end portion of the yoke 56 to move away from bearing contact against the actuating finger 65 of the switch 00. Thus, the V circuit of the driving motor 70 will be interrupted and the motor de-energized. It will be understood that the pivoting movement of the yoke 56 and the consequent disalignment of the driving shaft 82 and the driven shaft It of the gear mechanism will be compensated for in the universal joints #5.

Subsequent to de-energization of the driving motor E0 the continued rotation of the motor and associated gearing because of momentum forces will be translated into further tensioning of the coupling spring devices l8-86; and the irreversible character of the gear mechanism 12 will prevent subsequent reversal of movement so that the coupling springs 'I886 will remain tensioned pending recommencement of the firing operation.

Upon subsequent closing of the firing control switch and recommencement of the gun firing operation the action of the gun feed mechanism will initially relieve the conjestion in the feed throat 50 and the roll carrying yoke 50 will be immediately allowed to pivot back to the position of Fig. 3 whereupon the control switch 66 will again be closed, thus completing the circuit to the driving motor I0 whereby the latter will again be energized. Prior to attainment of full driving speed on the part of the motor 70 the coupling spring devices Hi-86 will extend from their previously tensioned conditions to make up for the deficiency of driving motor speed relative to the requirements of the gun feed mechanism. Upon subsequent attainment of full driving speed by the motor 10 the coupling spring devices will then function as simple driving elements; and thus the mode of operation will be repeated as above described until the contents of the magazine I4 are exhausted.

Also, it will be understood that by virtue of the arrangement of Figs. 3 and 4 the driving motor I0 is prevented from applying excessive torque to the driving r011 52 in relation to the cartridge feed requirements of the gun feed mechanism. Whenever the torque applied by the motor I0 to the driving roll 52 builds up to an excessive degree the reaction forces between the driving roller 52 and the cartridge belt portlon between the rolls and the gun will automatically cause the roller 52 to rock the yoke about its pivot 51 out of engagement with the actuating finger of the switch 60, whereupon the motor I0 will be deenergized pending reduction of the torque applied through the driving mechanism to a degree consistent with the requirements of the cartridge feeding operation.

Figs. 5 and 6 illustrate another form of driving motor control device for the feed assist mechanism of the invention. The machine un I0 is shown mounted upon a pair of stationary bearer tubes I00 which are in turn supported by any suitable fixed base means (not shown). The gun I0 is provided at its rear end with a pair of laterally extending collars IOI which engage the bearer tubes in longitudinally free sliding relation. At its opposite end the gun casing is provided with a pair of opposed struts I02 which extend into corresponding end portions of the bearer tubes I00. The struts I 02 are fitted with enlarged heads I03 at their inner ends which engage the inner walls of the bearer tubes I00 in free sliding relation. Compression springs I04 are arranged between the strut heads I03 and bearing plugs I04 which are fixed by means of pins I05 within the bearer tubes. Thus, the gun I0 is mounted upon the bearer tubes in such manner as to be slidable rearwardly thereon in response to recoil forces operating upon'the gun during firing thereof, against the action of the compression springs I04. Preferably the adjacent end portions of the bearer tubes I00 will be closed with airtight inserts I06 and suitable packing a at I01. Thus, the air within the bores of the bearer tubes I00 in the region of the springs I04 will be compressed during recoil movements of the gun upon the bearer tubes, whereby the compression of the air will assist the springs I04 in cushioning the recoil forces of the gun and in returning the gun between firing operations toward its position of rest as shown in Fig. 6. However, the resiliency of the springs I04 and the air compressing operations are regulated in view of the rapidity of the firing of the gun so that the gun is not returned to its completely inactive position as illustrtaed in Fig. 6 between successive recoil strokes thereof. Hence, whereas the position of the extreme outer end of the strut I02 is illustrated in Fig. 6 as being in registry with line A thereof, the range of its recoil stroke positions during continuous firing of the gun will be as between lines B and C of Fig. 6.

IA control switch H0 for controlling energize. tion of the feed assist driving motor is fixedly mounted by means of a bracket I I2 upon the insert I06 at the end of one of the bearer tubes I00 so as to be stationary and not subject to movement during recoil actions of the gun. A switch actuating finger II4 extends from the switch IIO into abutting registry at I I5 with the adjacent strut I02 of the recoil mechanism of the gun mounting, and the switch actuating elements are so arranged that when the strut I02 is in the guninactive position of Figs. 6 and 8 the switch finger I I4 is thereby maintained against the action of a spring device II5 within the switch H0 in such position as to allow the leaf spring contact member I I6 to be away from the fixed contact member II'I so as to open the electric circuit controlled by the switch IIO. Thus, whenever the gun I0 is inoperative the switch H0 is held open and the feed assist driving motor circuit is open. Upon commencement of the gun firing operation, however, the recoil strut I02 retreats to positions within the range of movement indicated by the lines B and C, thus (Fig. 6) allowing the finger I I4 to move under the force of the spring I I5 toward the right from the position of line A to the position of line D, whereupon the switch I I0 will be actuated to close the circuit to the feed assist driving motor.

Thus, as long as firing of the gun continues the switch I I0 remains closed, and the space between the contact finger H4 and the recoil strut I02 as marked between the lines D and C protects the switch finger II4 from hammering contact with the recoil strut during the gun firing operation.

Uponcessation of gun firing the gun returns to its position of rest relative. to the bearer tubes H asillustrated: by Fig. 6, whereupon the actuating finger of the switch H0 is moved by. the: recoil strut N32 to SIVitCh?O'fi position, thus de-energizing. the. feed assist driving motor. Thus, the feed assist driving mechanism is automatically controlled by firing operation of the gun Land, so long as'the gun continues to fire the feed assist mechanism will continu to be energized by the 'driVing motor. Thus, the energiza tionof the feed assist mechanism isat all times a direct function of actual firing of the gun,.and therefore the assist mechanism isr'operative only. at: such times as the gun requires feeding. V

. Although only a limited number o-f forms of the invention are shown and described in detail, it will be apparent to those skilled in the art that the invention is not so limited but that various changesmay be'made therein Without departing from the spirit .of the invention or the scopeof theappended claims.

Ihclaim:

1., A machine-gun ammunition feed mechanism comprising a support,. an ammunition. belt guide mounted upon: said support toextend into registry with the ammunition feed port of the machine gun, said'guide comprising a conduit-likeomemher adapted: to slidably'receive the belt in laterally confined relation, a belt driver movably mounted upon said: support andextending. into said conduit intermediat the ends thereof for,

driving engagement with the belt'to forceit to move through said? guide in ammunition. feeding direction toward said gun, motorimeans, elastic power transmission means coupling saidv motor means to said driver for actuatingithe latterxto feed thebelt through said guide towardthe: gun, elastic force means mounted upon said support and bearing against said driver to elastically urge said driver to. positionally move in thedirection of ammunition feeding toward said gun and to resist movementthereo-f in the directionopposite to thedirectionof belt feeding movement through said guide, and motor control" means. mounted uponsaid support in registry with-said driver and adapted to be actuated thereby to cause saidmot'or means'tobe de-energized upon movement-of said driver against the action of said elastic means.

2. A machine gun ammunition beltjfeed rneclranism comprising a support, an ammunition belt guide mounted upon said support toextend into registry with the ammunition feed port of the machine gun, said guide comprising a-conduit-like member adapted to slidably receive the belt-in laterally confined relation, a belt driver'movabl-y mountedupon' said support and extending into said conduit intermediate the ends thereoffor driving engagement with the belt to force it to move through said' guide in ammunition feeding direction toward said gun, motor meanscoupl'ed to said driver for actuating the latter to-feed the belt through said guide toward" the gun, said conduit-like member extending continuously to the feed port of the gun and constructed and'arran'ged to constrain the feed belt to linealfeedingmovement only, elastic force means niounteduponsaid support andbearing'against said driver to elastically urge said driver to positionally move in the 7 direction of ammunition feeding and to resistpositionalmovement thereof in the direction opposite to the direction of belt feeding movement through said. guide, and motor control means mounted upon said'support in' registry with said driver and adapted to be actuated thereby to cause said motor means to'be de-energized upon movement of said driver against the action of said elastic means.

, 3; A machine gun ammunition feed mechanism comprising a support, an ammunition belt guide mounted upon said supp to extend into registry with theammunition feed port of the machine -gurr,-said guide comprising a -conduit-like member adapted to slidably receive thev belt in laterally confined relation, a belt drivingsprocket movably mounted upon said support and extending into said conduit intermediate the ends thereof for geared engagement with the belt to force it to move through said guide in ammunition feedingdirection toward said gun, motor means coupled to said sprocket for rotating the latter to feed the belt through said-guide toward -th gun, said conduit-like member extending continuously to the feed port'ofthe gun andconstructed and arranged-to'constrain the feed belt to lineal feeding movement only, elastic force means mounted upon said support and bearing against said sprocket to elastically urg said driver to positionally move in the direction of ammunition feeding and to resist positional. bodily displacement movement thereof in the direction opposite to the direction of belt feeding movement through said guide, and motor control means mounted upon said suppo-rt'in registry with said sprocket and adapted'to be actuated thereby to cause said motor means to be de-energized upon movement of said sprocket'bodily against the actionsof said elastic means:

4. A machine gun ammunition feed mechanism comprising a support, an ammunition belt guide mounted upon said sup-port to extendinto registry with the ammunition feed port of the machine gun, said guide comprising a conduit-like member adapted to slidably receive the beltin laterally confined relation, a belt-driver movably mounted upon said support and extending into said conduit intermediate the ends thereof for driving engagerment'witli the belt to foroe it to move through said guiderin' ammunition feeding direction toward said gun, motor'm'eans coupled to said driver for actuating-the latter to feed the belt through said guide toward the gun, said conduit-lik member extending continuously to the; feed port of the gun; and constructed and arranged to constrain the feed" belt tolineal feeding. movementonly,

elastic force means mounted upon said support and bearingagainst sa'i'd driver to elastically urge said driver to positionally move in the direction-of ammunition feeding toward said gun and to resist bodily movement thereof in theidirection opposite to the direction o-fbeltfeeding movement through said guide; and motor control meansmounted upon said support in registry with said'driver and adapted to be actuated. thereby to cause said motor means to be de-energizedupon movement of said driver-against theaction of said elastic means in response to? increases of resistance by the gun to belt feeding operation of said driver.

JOHN C. TRO I I'ERV 

